1. Field of the Invention
The present invention relates to the general field of catalyst testing, generally classified in U.S. Patent Class 502 or 252.
2. Description of the Prior Art
Prior Art will include C and E News, Jan. 8, 1996, p.30 which teaches reactive plastics, and the many catalyst testing devices and processes known to the petroleum refining art. F. M. Menger, A. V. Fliseev, and V. A. Migulin, xe2x80x9cPhosphatase catalysts developed via combinatorial organic chemistryxe2x80x9d, J. Org. Chem. Vol. 60, pp 6666-6667, 1995. Xiang, 268 Science 1738 and Bricenol, 270 Science 273, both on combinatorial libraries of solid-state compounds; Sullivan, Today""s Chem. At Work 14 on combinatorial technology; Nessler 59 J. Org. Chem. 4723 on tagging of combinatorial libraries; Baldwin, 117 J. Amer. Chem. Soc. 5588 on combinatorial libraries.
3. Problems Presented by Prior Art
Catalyst testing is conventionally accomplished in bench scale or larger pilot plants in which the feed is contacted with a catalyst under reaction conditions, generally with effluent products being sampled, often with samples being analyzed and results subjected to data resolution techniques. Such procedures can take a day or more for a single run on a single catalyst. While such techniques will have value in fine-tuning the optimum matrices, pellet shape, etc., the present invention permits the scanning of dozens of catalysts in a single set-up, often in less time than required for a single catalyst to be evaluated by conventional methods. Further, when practiced in its preferred robotic embodiments, the invention can sharply reduce the labor costs per catalyst screened.
According to the invention, a multisample holder (support) e.g., a honeycomb or plate, or a collection of individual support particles, is treated with solutions/suspensions of catalyst ingredients to fill wells in plates, or to produce cells, spots or pellets, holding each of a variety of combinations of the ingredients, is dried, calcined or otherwise treated as necessary to stabilize the ingredients in the cells, spots or pellets, then is contacted with a potentially reactive feed stream or batch e.g., to catalyze biochemical reactions catalyzed by proteins, cells, enzymes; gas oil, hydrogen plus oxygen, ethylene or other polymerizable monomer, propylene plus oxygen, or CCl2F2 and hydrogen. The reaction occurring in each cell is measured, e.g. by infrared thermography, spectroscopic, electrochemical, photometric, thermal conductivity or other method of detection of products or residual reactants, or by sampling, e.g. by multistreaming through low volume tubing, from the vicinity of each combination, followed by analysis e.g. spectral analysis, chromatography etc, or by observing temperature change in the vicinity of the catalyst e.g. by thermographic techniques, to determine the relative efficacy of the catalysts in each combination. Robotic techniques can be employed in producing the cells, spots, pellets) etc. Each of these parameters is discussed below:
Catalysts: Biotechnology catalysts include proteins, cells, enzymes, etc. Chemical conversion catalysts include most of the elements of the Periodic Table which are solid at the reaction conditions. Hydrocarbon conversion catalysts include Bi, Sn, Sb, Ti, Zr, Pt, the rare earths, and many possible candidates whose potential has not yet been recognized for the specific reaction. Many synergistic combinations will be useful. Supported metals and metal complexes are preferred. The chemical catalysts can be added to the substrate (support) as elements, as organic or inorganic compounds which decompose under the temperature of the stabilizing step, depositing the element or its oxide onto the substrate, or as stable compounds.
Supports: Supports can be inert clays, zeolites, ceramics, carbon, plastics, e.g. reactive plastics, stable, nonreactive metals, or combinations of the foregoing. Their shape can be porous honeycomb penetrated by channels, particles (pellets), or plates onto which patches (spots) of catalyst candidates are deposited or wells in plates. Conventional catalyst matrix materials such as zeolites e.g. zeolite USY, kaolin, alumina, etc. are particularly preferred as they can simulate commercial catalysts.
Preparation: The catalyst candidate precursors can be deposited onto the supports by any convenient technique, preferably by pipette or absorbing stamp (like a rubber stamp), or silk screen. In preferred embodiments, the deposition process will be under robotic control, similar to that used to load multicell plates in biochemical assays. Many of the spots of catalyst will be built up by several separate depositions e.g. a channel penetrating a honeycomb can be plugged at one third of its length and the channel filled with a catalyst solution in its upper third, then the plug can be moved to the two-thirds point in the channel and a second catalyst pipetted in, then the plug can be removed and a third catalyst solution added, resulting in a channel in which reactants contact three catalysts successively as they flow through the channel. Catalyst can also be added by ion exchange, solid deposition, impregnation, or combination of these. The techniques of combinatorial chemical or biological preparation can preferably be utilized to prepare an array of candidate catalysts with the invention. Coprecipitates of two or more catalysts can be slurried, applied to the support, then activated as necessary. Catalysts can be silk screened onto a support plate or inside of a support conduit, and successive screenings can be used to add different catalyst combinations to different spots.
Stabilizing Step: Once the catalysts are in place on the support, any suitable technique known to the art can be used to stabilize, and/or activate the particular catalysts chosen, so they will remain in place during the reaction step. Calcining, steaming, melting, drying, precipitation and reaction in place will be particularly preferred.
Reactants: The Invention has utility with any reaction which can be enhanced by the presence of a catalyst, including biological reactions and inorganic and organic chemical reactions. Chemical reactions include polymerization reactions, halogenation, oxidation, hydrolysis, esterification, reduction and any other conventional reaction which can benefit from a catalyst. Hydrocarbon conversion reactions, as used in petroleum refining are an important use of the invention and include reforming, fluid catalytic cracking, hydrogenation, hydrocracking, hydrotreating, hydrodesulfurizing, alkylation and gasoline sweetening.
Sensors: The sensors used to detect catalytic activity in the candidate catalysts are not narrowly critical but will preferably be as simple as practical. Chromatographs, temperature sensors, and spectrometers will be particularly preferred, especially those adapted to measure temperature and/or products near each specific catalyst spot e.g. by multistreaming, multitasking, sampling, fiber optics, or laser techniques. Thermography, as by an infrared camera recording the temperature at a number of catalyst sites simultaneously, is particularly preferred. Other suitable sensors include NMR, NIR, TNIR, electrochemical, fluorescence detectors, Raman, flame ionization, thermal conductivity, mass, viscosity and stimulated electron or X-ray emission Sensors can detect products in a gas or liquid stream or on the surface of the support.
Endothermic reactions exhibit reduced temperature at best catalysts. Some sensors employ an added detection reagent, e.g. ozone to impart chemiluminesce.
Taggants: Optionally taggants (labels) can be added to identify particular catalysts, particularly where particles are employed as supports for the catalysts. These taggants can be conventional as discussed in the literature. Taggants can be chemicals which are stable at reaction conditions or can be radioactive with distinctive emissions. The techniques of combinatorial chemistry will be applicable with taggants as well as with catalysts chosen to suit the particular reaction to be enhanced by the catalyst.
Batch or Continuous: While the invention will be preferred on a flow basis, with reactants flowing by the catalyst spots under reaction conditions, batch testing e.g. in a stirred autoclave or agitated containers, can be employed, particularly in biological reactions.
Temperatures, pressures, space velocities and other reaction conditions: These will be determined by the reactants and reaction. Elevated pressures can be provided as reaction conditions by encasing the support in a reaction chamber with a sapphire or similar window for observation by the sensing means, or with pressure-tight leads extending through the reactor walls.
The present invention is useful in the testing of catalysts for biotechnology, for promotion of gas phase and liquid phase reactions; under batch or, preferably, continuous flowstream conditions; at elevated, reduced or atmospheric pressure; and saves both elapsed time and labor in screening for improved catalysts to promote a desired reaction.